It is difficult to attach lifting lines to a seismic float, which is part of a seismic subarray, while the float is alongside a tow vessel, due to differential motions between the float and the tow vessel. It is considered quite difficult and dangerous for men to reach over the side with grapples to try to put lines on the seismic float, particularly when the tow vessel is much larger than the seismic float.
One conventional way of attaching lines to the seismic float is to leave "pigtails" trailing from the seismic float. These pigtails are captured using poles and brought onboard the tow vessel for attachment to lift lines. However, this procedure is very cumbersome for recovering, for example, from a 300-foot long tow vessel, a seismic float which may be up to 60 feet long, weigh up to 25,000 lbs., and have attached gear such as seismic guns and umbilical cables which are subject to entanglement. Accordingly, considering both the size, unwieldy dimensions, and motions of a seismic float in the water, it is desirable to have a recovery system which avoids the manifest problems of the art.
Applicant is not aware of any prior references which, in his judgment as one skilled in the art of seismic floats, would anticipate or render obvious the novel recovery method and apparatus of the invention. U.S. patent application Ser. No. 516,158 filed July 21, 1983, now U.S. Pat. No. 4,516,517 issued May 14, 1985 and having a common assignee, is relevant to the present invention.